1. Field of the Invention
The present invention relates to a fan driven by a tip turbine and, in particular, to one which drives a fan to rotate by supplying a fluid to a tip turbine rotor cascade provided at the outer periphery of the fan.
2. Related Background Art
It has conventionally been proposed to employ a fan driven by a tip turbine, which drives a fan to rotate by supplying a fluid to a tip turbine rotor cascade provided at the outer periphery of the fan, in VTOL (Vertical Take-Off and Landing) aircrafts. For example, Japanese Patent Application Laid-Open No. 2003-293702 discloses a structure which supplies a working fluid to a tip turbine rotor cascade through a supply duct from the intake side toward the exhaust side of the fan, returns the working fluid having passed the tip turbine rotor cascade toward the intake side of the fan through a return duct, and then supplies the working fluid to the tip turbine rotor cascade again from the intake side toward the exhaust side of the fan, so as to drive the fan to rotate.